Device for reducing thickness of thin sheet material



Aug. 16, 1949. c, w HANSELL 2,479,353

DEVICE FOR REDUCING THICKNESS OF THIN SHEET MATERIAL Filed Nov. 1, 1943 INVENTOR dlwmende 1111 m BY #i mw ATTORNEY Patented Aug. 16, 1949 DEYICE MR REDUCING THIKNESS- E THIN SHEET MATERIAL Clarence. W; Hansell, Port Jefferson, N. YL, as

signor to Radio Corporation ofAmeri'ca, a corporatiorr ofDeIaware AppIicatiomNovember 1, 1943, Serial! Nm.508:, 626- 5 Claims. 1'.

This invention relates to apparatus. and means. for. reducing. the thickness oi thin. sheet mate.- riaL. and for. reducing the. diameter. of, wires.

An object. of. this invention is to provide amachine which will. eflicientl'y: anduniiormly reduce. the thickness of'thinsheetmaterial, such as sheet. steel for transformer laminations, without. the. use of precision rolls,

Another object. of invention. is to; ravide means for reducing the. diameter oi. wires without. the use of precision dies.

A feature of the invention is a. novel arrangement of a high frequency inductionheating device and two interlinked" moving, elements, moaement of which automatically stretches the. ma erial by a predetermined amount. These interlinked elements may, for example, be rotating; drums having different peripheral speeds for stretching the sheet stock. or wires.

As an example of a need for, and. application. of the invention,- it is noted that,. in. the development' of pulse transformers for use inradar and pulse communication systems there is a great need for extremely thin laminations Qt magnetic material. Thin iron laminations, or ribbons, in the order of .001" thick have not been obtainable in ordinary trade channels.

Objections to the. manufacturing of extremely thin laminations are that they are hard to roll to. such small dimensions They require extreme precision in roller dimensions and finish and the. laminations or ribbons are hard to handle without wrinkling after they are rolled. Furthermore, because of the thinness of the sheet material, a given weight and volume of core material occupics the time of the rolling equipment in. inverse proportion to the thickness of the sheet material.

An outstanding advantage of the invention is that it permits adjustment of the dimensions of laminated materials which, at present, cannot be handled satisfactorily by rolling or drawing because of differences in the hardness and viscosity of the laminated materials.

It should be understood that the principle of this invention is applicable to all sorts of stretching or drawing operations on a wide variety of materials, including metals, plastics, etc.

This invention will best be understood by referring to the accompanying drawing in which:

Fig. 1 is a perspective view of the device of the invention as applied to reducing the thickness of thin sheet material, and

Fig. 2 is a perspective view of a device of the invention for reducing the diameter of wires.

Referring now to Fig. 1 of the drawing, to accomplish the reduction of the thickness dimension of sheet material a pair of traction drums I and 2 are supported from a common base, not shown. Sheet stock material 6 from a reel 1 is passed over the two. drums I and. 2 or diiferent diameters which are coupled. together by means of. sprockets 3, and 4. and. chain. 5,. or. suitable gears, the. arrangement. of coupling or gearing being such. asv toprovide a fixed ratio of. tam lutions. per unit of; time between. drums. I and 2.. The ratio of speed of rotation and. the diameters. of the drums determines the. amount 0t stretchi g. of. the material. and: the reduction in thickness. Prevention of any slippage of. the sheet material, as it passes over the drums. L and 2,..i maintained. by means of the. idler rollers l2: and I3t,

Inthe operation of the.- device of this; invert-- tion, the drums I- and 2. as coupled together, are: subject to a more or less constant. torque, from the power source driving shaft 2a, which tries. to, stretch the material. If the. torque is great. enough the material: may be stretched cold but thespresent. example it is; assumed that the torque i so adjusted that there is. no; rotation oi the; drums and no stretching if the: material: is. cold. A portion of the;- sheet; material, a point be tween drums t and 2,. is. new subjected to. heating by any suitable means in this example by high frequency induction. The high frequency power is applied to electrodes such as the radio frequency coupling devices 9 and Ill from source I I. The frequency from source I I is intended to be above 20,000 cyclesper second. This high frequency power will raise the temperature of a portion of thematerial toor beyond the softening or annealing temperature. By this arrangement the metal strip material is uniformly heated by' radio frequency induction in a radio frequency field derived from an oscillator II which may have a frequency of approximately 1 meaacycle to heat the metal strip to a temperature range of 1,000'F. to about 1,500" F. As soon as the proper temperature is reached the drums I and 2, which before could not move in response to the torque without stretching the material, will begin to move as the heated material softens and stretches. It is to be noted that the drums cannot turn without stretching the material and the material cannot stretch until it has. reached a softening temperature. Therefore, as heat is. applied and the material reaches the softening temperature the drums rotate automatically in response to the applied torque but always at. a rate such that the hottest part of the material is at the softening temperature. If the material is not hot enough the movement slows down unt'r it is hot enough while, on the other hand, if it is too hotthe movement speeds up until it is cooler, be cause of shorter time of exposure to heating. The rate of motion or stretching is automatically controlled by the rate of heating and results in uniform working on stretching of the, material. The apparatus assembly is one which controls its own speed of operation, to match the heating power input, without the need for any compli cated control system. The degree of stretch of the material, or percent elongation, is of course determined by the ratio of peripheral motions of the drums, which are linked together so that the peripheral motions are in a constant ratio. Thus, if the peripheral motion of drum 2 is twice that of drum I, in Fig. 1, then the elongation of the material will be two to one.

Preferably the material, as it comes from the machine, i wound directly onto core forms to make the cores of the transformers. represents either the transformer core material being wound to form a core or storage spools on which the material is wound for rewinding or other use later.

Referring now to Fig. 2, the application of'the invention a applied to drawing wire to a smaller diameter is shown. A wire 23 of some stock di-- ameter, wound on spool 24, is drawn over drums 2| and 22, which are somewhat concave on their outer cylindrical surface, in the manner usual to drawing operations, that i three or four turns of wire around each drum. Drums 2! and 22 are coupled together by means of a chain 215 and sprockets 21 and 28 in the same manner as in Fig. 1, and torque is applied to the shaft of drum 22. High radio frequency induction or another suitable form of heating is applied by drawing the wire through a radio frequency coupling coil or work coil located at a point 29. The radio fre quency coil connect to a source of high frequency similar to that of source 'll mentioned above. drums and the rate of motion of the wire is automatically controlled by the rate of heating.

An advantage of the system of this invention is that the thickness of the finished material is" automatically held to the same percentage of tolerance as was obtained in the original stock; material and the necessity. for extremely close. calculation and control of roll dimensions and precision of fine dies as now required to roll very thin laminations or draw fine wires is avoided.

I contemplate, besides chains and gears, the use of adjustable ratio transmissions of which standard types are available in the market, for coupling the drums together. In this case any.

ratio of thickness or diameter reduction is obtainable on a moments notice, by mere adjustment of the transmission ratio. Such an arrangement can be of great value in transformer manufacturing plants and other establishments where standard thicknesses and diameters are not adequate to meet all the required conditions of design and for which special drawing and rollin operations are now required.

In the preparation of thin laminations of magnetic material, it has been found that the permeability of the material is substantially greater. in the direction of Working than in other directions. This increase of permeability in the lengthwise direction will be even greater in material prepared by the present process than it is in material prepared by rolling and drawing operations of the prior art.

Also the stretching process will have a beneficial effect upon the mechanical strength of some materials.

The process and machine of this invention are also applicable to nonmetallic plastic materials, as for example, in the manufacturing of some light polarizing material a stretching process is used to suitably orient submicroscopic light po- Spool l4 The wire is thus heated between the larizing crystals. This invention is well adapted to performing such a stretching operation.

Likewise the process may be used in producing thin sheets and fibers of thermoplastic materials of all kinds, such as are used as covering and produce a ratio of peripheral speeds having a value greater than one, a source of radio frequency power, a radio frequency heating device connected to said radio frequency source and having electrodes disposed above and below the plane in which the thin sheet material is adapted to pass to raise the temperature beyond the an nealing temperature thereof, whereby the thin sheet material running over said drums. is

stretched, in a fixed ratio when the drums rotate.

2. A radio frequency heating device for reduc-- ing the thickness of thin sheet material, comprising two rotatable drums for working and stretching said thin sheet material, each of said drums being operated together with different peripheral speeds and maintained at a substantially constant torque, operating means including a sprocket and chain device to rotate said drums, a source of radio frequency, a pair of raclio frequency electrodes connected to said radio frequency source, one of said electrodes being located above the thin sheet material and the other electrode being located below said thin sheet material to permit the heating and stretching thereof, whereby the thin sheet material'is reduced in thickness when said drums are rotated. 3. A radio frequency heating device for reducing the thickness of thin iron transformer lami-.

nations to maintain the permeability of the lamination greater in the direction of the working and stretching than in the other direction, comprising a pair of drums, said drums being operated together at different peripheral speeds and.

maintained at a substantially constant torque, a source of radio frequency heating, a radio frequency heating. device located. adjacent said. drums to permit the heating and stretching of said iron transformer laminations and to raise the temperature beyond the annealing temperature whereby said laminations are reduced in.

thickness.

. 4. A device for working and stretching sheet material, comprising a pair of drums, means to rotate said drums at a substantially constant;

torque, a source of radio frequency which is operated above 20,000 cycles per second, a coupling device through which the sheet material is passed to raise its temperature beyondthe-annealing temperature, said coupling device being con v nected to said source of radio frequency, means to rotate and couple said drums together to produce a ratio of peripheral speeds having a value greater than one, to forcethe heated sheet material to stretch, whereby the material running over the drums must stretch in a fixed ratio when.

a source of radio frequency power, a radio ire-5 quency heating device connectedtosaid radio frequency source and having electrodes disposed 5 above and below the plane in which the thin sheet material is adapted to pass, and means for automatic self adjustment of the speed or said drums to hold the softening temperature of the thin sheet material in the general location of said electrodes.

CLARENCE W. HANSELL.

REFERENCES CITED The following references are of record in the 10 Number file of this patent:

UNITED STATES PATENTS Number Name Date 342,040 Reese May 18, 1886 15 1,064,936 Scott June 17, 1913 1,347,917 Sheperdson July 27, 1920 1,422,085 Davies July 11 ,1922 1,718,806 Witting June 25, 1929 Number Name Date 1,977,214 Steckel Oct. 16, 1934 2,051,949 Inscho Aug. 25, 1936 2,169,711 Sendzemir Aug. 25, 1939 2,226,448 Simons Dec. 31, 1940 2,332,803 Lorig Oct. 26, 1943 2,335,190 Minich Nov. 23, 1943 FOREIGN PATENTS Country Date 20,691 Great Britain Oct. 29, 1894 213,027 Great Britain Mar. 27, 1924 475,931 Germany May 6, 1929 OTHER REFERENCES Principles Underlying Radio Communication," Pamphlet #40, Signal Corp. U. S. Army, 1921 edition, page 191. 

